Method and installation for braking a moving body

ABSTRACT

A method of braking a body which moves along a surface in an ambient medium, said method comprising forming liquid-gas foams in the path of the moving body, the density of these foams being greater than that of the ambient medium and preferably increasing in density in the direction of movement of the moving body.

United States Patent 1 Duthion et a1.

[11] 3,738,2S2 [4 1 June 1 2, 1973 METHOD AND INSTALLATION FOR BRAKING A MOVING BODY Inventors: Louis Duthion, Paris; Claude Charles Doyotte, Le Plessis-Robinson, both of France Assignee: Bertin & Cie, Paris, France Filed: Sept. 14, 1970 Appl. No.: 71,676

Foreign Application Priority Data Sept. 12, 1969 France 6931079 U.S. C1. 104/249, 188/34 Int. Cl 861k 7/00 Field of Search 104/249, 250, 252,

[56] References Cited UNITED STATES PATENTS 3,301,335 1/1967 Snelling 293/52 F X Primary Examiner-Gerald M. Forlenza Assistant Examiner-Robert Saifer Attorney-Brufsky, Staas, Breiner and Halsey [57] ABSTRACT A method of braking a body which moves along a surface in an ambient medium, said method comprising forming liquid-gas foams in the path of the moving body, the density of these foams being greater than that of the ambient medium and preferably increasing in density in the direction of movement of the moving body.

18 Claims, 6 Drawing Figures PATENIEU JUN I 21973 sum 2 or g METHOD AND INSTALLATION FOR BRAKING A MOVING BODY Certain bodies which move at high speeds, faster than the velocity of sound, must be recovered undamaged, either for reasons of economy or because these moving bodies carry some recording apparatus; such is the case, for example, with experimental guided carriages traveling along a track. The braking of such moving bodies has already been obtained with the help of aerodynamic or hydraulic means, or of mechanical or magneto-electrical friction devices. Most often, at least part of the braking means is installed on the moving body, consequently increasing the total weight of the moving body, the energy required for launching said body and the braking distances.

To reduce these inconveniences and especially to allow for a reduction in braking distances, the present invention provides an improved method and installation for braking a body which moves along a surface, in which the braking effect is obtained by a penetration of the said moving body into at least one liquid-gas foam of greater density than that of the ambient medium, preferably a density which increases in the direction of movement of the said moving body.

Said liquid-gas foam or foams are obtained by blowing a gas (e. g., air) under pressure through one or more foam-producing liquids. Gas-blowing means may be used which include a gas-permeable wall-means, such as a membrane provided with gas blower openings. Preferably, the abovementioned surface is a track which is provided with wall means adapted to contain the said liquid-gas foam or foams at the time of braking of the moving body. The liquid-gas foam or foams may be produced on the track itself, for instance in one or several gutters in which said foam-producing liquid or liquids have been spread beforehand. The braking force due to the drag of the moving body in the liquidgas foam is approximately proportionate to the square of the displacement speed of the said moving body. Now to reduce the stopping distance, it is desirable to keep said braking force as constant as possible. This may easily be obtained by distributing liquid-gas foams of different densities on the track so that in the course of braking, the moving body penetrates into liquid-gas foams of greater and greater densities.

The invention also deals with means to protect the liquid-gas foam or foams from bad weather and with means to increase the efficacy of said foams.

It is quite evident that the liquid-gas foam or foams could be produced with the help of conventional emulsifiers, similar to the foam-extinguishers used in firefighting equipment.

The description whichnow follows with reference to the accompanying drawings, given by way of nonlimiting examples, will help to show how the invention may be carried into practice. In the drawing,

FIG. 1 is a sectional view showing a first form of a braking installation embodying the present invention;

FIG. 2 is a partial plan-view on a reduced scale, of the installation shown in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

FIG. 4 is a perspective view of a second form of braking installation embodying the present invention, and

FIGS. 5 and 6 are perspective views respectively showing a detail of the installation shown in FIGS. 4 and 1.

Referring now to FIGS. 1 to 3, the surface on which a body 2 moves at high speed is a track 1 provided with protruding walls 1a. The moving body is, for example, a supersonic experimental vehicle which is guided by the protruding walls 1a. Side-walls 3 also protruding from the track 1, bound together with said track one or several gutters 4. The bottom part of said gutters 4 is adapted to be covered beforehand with foamproducing liquid 40. On this bottom part are placed tubes 5 which are formed with multiple perforations 5a (see FIG. 6). Said perforations are used to blow through the liquid 40, a multiplicity of jets of air or another gas under pressure, whereby to bring about, in the path of the moving body 2, the formation of at least one liquid-gas emulsion or foam 400 the density of which is greater than the density of the ambient medium (generally air) which surmounts the track 1.

The foam-producing liquid 40 is similar to all the foam-producing liquids used in foam-extinguisher equipments for fire-fighting, which liquids and their properties are well-known to those skilled in the art. Pipe systems 6 permit refilling the bottom of the gutters 4 with the foam-producing liquid 40.

In another arrangement shown in FIG. 6, the pipe systems 6 are removed and the gutters are fed beforehand with foam-producing liquid 40 through one or several of the air or gas tubes 5.

In another arrangement shown in FIGS. 4 and 5, the track is provided with protruding walls 1b having portions 1c which cooperate with the moving body 2. The gutters 4 are bounded by the side-walls 3 and by the track 1 provided with the said protruding walls 1b. The blowing of air or gas is achieved through a porous membrane 8 covering one or several grooves 7 which are connected to a source of air or another gas under pressure.

With reference to FIG. 2, it can be seen that the gutter 4 can be divided into several sections 9a, 9b, 9c by transversal, substantially liquid-tight partitions, such as 10. Different foam-producing liquids 40 are introduced into each of the said gutter sections whereby to permit the production of liquid-gas foams 400 the density of which is different from one section to the next and greater than that of ambient medium. For example, if the movement of the body 2 is in the direction of the arrow F, the value of the density of the foam in section 9a will be less than that of the foam in section 9b, which will be less than that of the foam in section 9c and so forth. Thus, the body 2 penetrating successively into sections 9a, 9b, 90, etc. will be obstructed by liquid-gas foams whose progressively increasing densities will allow compensation for the reduction of braking force due to the progressive decrease of speed of said body.

In FIGS. 1 and 4, there are shown substantially vertical walls 11 which are higher than the walls 3. The purpose of the walls 11 is to protect the liquid-gas foams formed on the track from the ambient medium, as said medium could possibly displace the foams or modify their homogeneity.

Similarly, above the track 1 is shown a roof 12 the purpose of which is to protect the foams from bad weather. The walls 11, the track 1 and the roof 12 bound together a covered channel which extends parallel to the path of the moving body 2 and includes said path. The cross-sectional area of this channel will preferably be variable along said path; it will be larger in the zone where braking begins and where the speed of the moving body is high, smaller in the zones where said speed is reduced. Between the walls 11 and the track, one or several permeable walls 13 may be placed, said walls being, for example, in the shape of a network the mesh dimensions of which will preferably decrease in the direction of the movement of the body 2. A similar permeable wall 14 may be placed between the roof l2 and the track. One of the reasons for this arrangement is to reduce the quantity of foam surmounting the track.

The operation of the braking installation is as follows: Before the launching of the experimental vehicle or body, different foam-producing liquids 40 are sent through the tubes 5 or 6 to cover the sections 9a, 9b, 9c, etc., of the gutter 4, with different sheets of foamproducing liquid, as has been indicated previously.

Then the liquid-gas foams 400 are produced by blowing air or gas under pressure through the tubes 5. When the volume bounded by the permeable walls 13, 14 is filled with foam, the braking installation is ready to operate.-

The braking of the vehicle 2 can then be carried out according to the following successive stages:

in a first stage, the vehicle is braked due to its aerodynamic drag in the ambient medium;

a second stage begins when the vehicle 2 penetrates into the section 9a where it meets a liquid-gas foam whose density is greater than that of the ambient medium, but still comparatively low, so that the braking force does not reach too high a value which would result in an abrupt slowing-down of said vehicle;

until the complete stop, the next stages then succeed each other gradually as the vehicle penetrates into sections 9b, 9c, etc. meeting in them denser and denser foams. When the vehicle penetrates into a foam, it displaces said foam toward the front, toward the sides, toward the top and the bottom. The foam has to be able to be displaced especially toward the sides and top without encountering too high a resistance. The walls 11 and the roof 12 must, therefore, be placed at an appropriate distance from the track so that there will not be any harmful interactions. Before encountering the walls and roof, the foam which is displaced by the vehicle 2 must pass through the permeable walls l3, 14 which should have sufficient permeability to avoid the building up of too high an overpressure. The permeability of these permeable walls may be suitably chosen, as mentioned hereinbefore, to vary the effectiveness of the foams, particularly when at the end of the course the vehicle speed is comparatively low.

It is evident that modifications may be made to the embodiments which have just been described, notably by a substitution of equivalent technical means, without departing thereby from the spirit of the present invention.

What is claimed is:

1. An installation for braking a moving body traveling along a surface in an ambient medium, comprising means for bounding, in cooperation with said surface, a channel which extends parallel to said path of the moving body and includes said path;

means for spreading foam-producing liquid over at least a part of said surface within said channel; and

means for blowing gas under pressure through said foam-producing liquid, whereby to generatein the path of the moving body at least one liquid-gas foam of greater density than that of the ambient medium, which foam forms a fluid obstruction for said moving body.

2. An installation as claimed in claim 1, further comprising means for bounding on said surface at least one gutter for containing said foam-producing liquid.

3. An installation as claimed in claim 2, wherein said bounding means for said gutter comprise wall means protruding from said surface and extending parallel to the path of the moving body.

4. An installation as claimed in claim 1, wherein said blowing means include duct means extending in the vicinity of said surface and having gas-permeable wall means the outer side of which is in contact with said liquid, and means to feed said duct means with gas under pressure.

5. An installation as claimed in claim 4, wherein said gas-permeable wall means comprise a perforated wall.

6. An installation as claimed in claim 4, wherein said gas-permeable wall means comprise a porous membrane.

7. An installation as claimed in claim 4, wherein said duct means extend parallel to the path of the moving body.

8. An installation as claimed in claim 1, further comprising means to divide said channel into at least two sections set up one after the other in the direction of movement of the moving body, wherein said spreading a guideway for guiding the moving body in apath along said surface;

means comprise means for spreading different foamproducing liquids over said sections, whereby to generate liquid-gas foams which are different from one section to the next, the density of these foams being greater in the second section traveled through by the moving body than in the first section traveled through.

9. An installation as claimed in claim 1, wherein the channel-bounding means comprise walls protruding from said surface and extending parallel to the path of the moving body.

10. An installation as claimed in claim 9, wherein at least one of said protruding walls serves to guide the movement of the moving body.

11. An installation as claimed in claim 1, wherein the channel-bounding means comprise walls protruding from said surface and extending parallel to the path of the moving body, and a covering roof disposed above the said protruding walls.

12. An installation as claimed in claim 11, wherein said protruding walls and said covering roof are arranged so that the cross-sectional area of the channel decreases in the direction of movement of the moving body.

13. An installation as claimed in claim 1, wherein the channel-bounding means comprise permeable walls.

14. An installation as claimed in claim 13, wherein the said permeable walls have a permeability which decreases in the direction of movement of the movin body.

15. An installation as claimed in claim 13, wherein the said permeable walls are in the shape of a network.

6 16. An installation as claimed in claim 15, wherein the density of these foams, greater than that of the said network has meshes the dimensions of which deambient medium, being greater in the second seccrease in the direction of movement of the moving i l d h h b h moving b d h i bodythe first section traveled through, said foams form- An mstananon for braking movmg body travel 5 ing successive fluid obstructions for said moving ing over a surface in an ambient medium, comprising: body means for bounding, in cooperation with said surface, a channel which extends parallel to the path A method for braking a movmg body travelmg of the moving body and includes Said path over a surface in an ambient medium, comprising the means for dividing said channel into at least two secst ep of generatmg m h path movmg body dons set up one after the other in the direction of uid-gas foams the density of WhlCl'l is greater than that movement f the moving body; and of the ambient medium and increases in the direction means placed in each of said sections to generate, in Of movement of the moving dy, Said foams forming the path of the moving body, liquid-gas foams successive obstructions for said moving body. which are different from one section to the next, 

1. An installation for braking a moving body traveling along a surface in an ambient medium, comprising a guideway for guiding the moving body in a path along said surface; means for bounding, in cooperation with said surface, a channel which extends parallel to said path of the moving body and includes said path; means for spreading foam-producing liquid over at least a part of said surface within said channel; and means for blowing gas under pressure through said foam-producing liquid, whereby to generate in the path of the moving body at least one liquid-gas foam of greater density than that of the ambient medium, which foam forms a fluid obstruction for said moving body.
 2. An installation as claimed in claim 1, further comprising means for bounding on said surface at least one gutter for containing said foam-producing liquid.
 3. An installation as claimed in claim 2, wherein said bounding means for said gutter comprise wall means protruding from said surface and extending parallel to the path of the moving body.
 4. An installation as claimed in claim 1, wherein said blowing means include duct means extending in the vicinity of said surface and having gas-permeable wall means the outer side of which is in contact with said liquid, and means to feed said duct means with gas under pressure.
 5. An installation as claimed in claim 4, wherein said gas-permeable wall meaNs comprise a perforated wall.
 6. An installation as claimed in claim 4, wherein said gas-permeable wall means comprise a porous membrane.
 7. An installation as claimed in claim 4, wherein said duct means extend parallel to the path of the moving body.
 8. An installation as claimed in claim 1, further comprising means to divide said channel into at least two sections set up one after the other in the direction of movement of the moving body, wherein said spreading means comprise means for spreading different foam-producing liquids over said sections, whereby to generate liquid-gas foams which are different from one section to the next, the density of these foams being greater in the second section traveled through by the moving body than in the first section traveled through.
 9. An installation as claimed in claim 1, wherein the channel-bounding means comprise walls protruding from said surface and extending parallel to the path of the moving body.
 10. An installation as claimed in claim 9, wherein at least one of said protruding walls serves to guide the movement of the moving body.
 11. An installation as claimed in claim 1, wherein the channel-bounding means comprise walls protruding from said surface and extending parallel to the path of the moving body, and a covering roof disposed above the said protruding walls.
 12. An installation as claimed in claim 11, wherein said protruding walls and said covering roof are arranged so that the cross-sectional area of the channel decreases in the direction of movement of the moving body.
 13. An installation as claimed in claim 1, wherein the channel-bounding means comprise permeable walls.
 14. An installation as claimed in claim 13, wherein the said permeable walls have a permeability which decreases in the direction of movement of the moving body.
 15. An installation as claimed in claim 13, wherein the said permeable walls are in the shape of a network.
 16. An installation as claimed in claim 15, wherein said network has meshes the dimensions of which decrease in the direction of movement of the moving body.
 17. An installation for braking a moving body traveling over a surface in an ambient medium, comprising: means for bounding, in cooperation with said surface, a channel which extends parallel to the path of the moving body and includes said path; means for dividing said channel into at least two sections set up one after the other in the direction of movement of the moving body; and means placed in each of said sections to generate, in the path of the moving body, liquid-gas foams which are different from one section to the next, the density of these foams, greater than that of the ambient medium, being greater in the second section traveled through by the moving body than in the first section traveled through, said foams forming successive fluid obstructions for said moving body.
 18. A method for braking a moving body traveling over a surface in an ambient medium, comprising the step of generating, in the path of the moving body, liquid-gas foams the density of which is greater than that of the ambient medium and increases in the direction of movement of the moving body, said foams forming successive obstructions for said moving body. 